The use or desire to use stationary devices for applying rotating clutch torque-transmitting mechanisms is becoming more popular. These devices are being considered because they permit the use of electric motor apply mechanisms and simpler hydraulic apply mechanisms.
Generally, the electric motor devices also include what is commonly termed a torque-to-thrust apparatus that converts a rotary input to an axial thrust, which in turn provides the required force for torque-transmitting mechanism engagement. The hydraulic apply devices have non-rotating pistons supplying the required force for torque-transmitting mechanism engagement. A thrust bearing is disposed between the non-rotating input mechanism, either hydraulic or electrical, and the apply plate for the torque-transmitting mechanism. While the thrust bearing is capable of transmitting the required apply force, it would be more desirable if the apply force could be reduced or eliminated after the torque-transmitting mechanism is applied to reduce bearing size and eliminate friction loss.